1. Field of the Invention
This invention relates to gravity-driven car racing, specifically an improved electrical timing start switch for race tracks such as used in the popular Pinewood Derby race.
2. Prior Art
Millions of Pinewood Derby races have been run since the inception of the race in 1953, mostly by Cub Scouts and their parents. But the currently available race tracks have a problem in the way electrical car start timers are turned on. Refer to the prior art FIG. 1 which points out a typical start mechanism, a version of which is shared by all prior art tracks. The typical location of a start gate is at the top of an initial elevated track portion called a ramp. A spring force is supplied by strong rubber bands or a spring arrangement such as shown in FIG. 1. When trigger action allows the start posts to rotate, thus releasing the cars, the lever of a common micro switch is released by the start post support bar. The movement of the micro switch lever applies or releases pressure that activates an internal snap-action contact closure inside the micro switch. This final action then triggers an electronic race timer. So first there is a start post support bar release, such movement in turn moving the micro switch lever, and then this lever causing in turn compression or release of the internal snap-action switch. This sequence of events leads to inaccurate start times. In such a conventional start switch arrangement, there is substantial variability in the time elapsed from the instant the start posts allow gravity forces to begin to move the cars until the micro switch contacts send a start signal to the race timer. Race winners can be decided by timer differences on the order of a tenth of a millisecond, and the prior art spread in race starting times may typically be tens of milliseconds. This variability can lead to an undesirable spread in race times for repeat runs of a car down the track. Thus, the true performance capability of a car may not be recorded. Also, simulation models of gravity cars are constantly improving, and these require precise initial conditions that force begins when time begins. Thus the measured start time data used to test the models needs to be accurate.
Referring again to prior art FIG. 1, we see that the items associated with the prior art start gate are mounted on a brace 17 or on other ramp member such as a main support leg 16 or the side of the ramp 19. A plurality of start posts 22 are supported by a wooden or metal bar 23 which is mounted to the ramp underside by a hinge with pivot 24. A lever 25 supports the bar 23 in a cocked position as shown with spring 26 stretched. Whenever the lever 25 is moved in the arrow direction, the bar 23 rotates around hinge pivot 24, allowing a micro switch lever 28 at the bottom of the start micro switch 27 to drop. This drop causes the internal contacts in the micro switch to send a start signal to a race timer through the wire pair 21. The lever 28 has flexure and there may be variations in the positioning of the micro switch itself relative to the bar 23. These also add uncertainties in the timing start signal turn on relative to the actual motion onset of car 20.